The use of fastening devices for the closure of containers, including plastic bag bodies, is generally known. Furthermore, the manufacture of fastening devices made of plastic materials is generally known to those skilled in the art relating to closure devices, as demonstrated by the numerous patents in this area.
A particularly well-known use for fastening devices is in connection with flexible containers, such as bag bodies. The closure device and the associated container may be formed from thermoplastic materials, and the closure device and sidewalls of the container can be integrally formed by extrusion as a single piece. Alternatively, the closure device and sidewalls may be formed as separate pieces and then connected by heat sealing or any other suitable connecting process. The closure devices when incorporated as fasteners on bag bodies have been particularly useful in providing a closure means for retaining the contents within the bag body.
Conventional closure devices utilize mating male and female closure elements which are occluded. When conventional closure devices are employed, it often is difficult to determine when the male and female closure elements are occluded. This problem is particularly acute when the closure devices are relatively narrow. Accordingly, when conventional closure devices are employed, there exists a reasonable likelihood that the closure device is at least partially open.
The occlusion problem arises from the inability of a user to perceive when the male and female closure are occluded to form a seal between the contents of the bag and the environment external to the bag. A number of solutions to this problem have been attempted. For example, U.S. Pat. Nos. 4,186,786, 4,285,105, and 4,829,641, as well as in Japanese patent application No. 51-27719, disclose fasteners that provide a visual indication that the male and female closure elements are properly occluded. Specifically, a color change means for verifying the occlusion of the male and female members of the closure is provided wherein male and female members having different colors are employed, and, upon occlusion, provide yet a different color. For example, the female member of the closure may be opaque yellow and the male member of the closure may be translucent blue. Upon occlusion of the male member and female member a composite color with a green hue results. This use of a color change greatly improves the ability of the user of the interlocking closure device to determine when the male and female members are occluded.
The change in color that is viewed when dissimilarly colored male and female members are occluded is demonstrated in a commercially available product sold under the trademark GLAD-LOCK (Glad-Lock is the registered trademark of The Glad Products Company, Oakland, Calif.). This color change effect may be enhanced by the incorporation of a color change enhancement member in the closure device, as disclosed in U.S. Pat. No. 4,829,641.
However, if the first fastening strip is opaque and the second fastening strip is translucent, the color change can only be observed from the translucent side of the closure device. Therefore, one of the objects of this invention is to provide visual confirmation of occlusion from both sides of the closure device.
In addition, another object of this invention is to provide a visual confirmation of occlusion wherein one of the fastening strips can be transparent.
Furthermore, color-blind users may not be able to perceive the color change effect. Thus, a further object of the invention is to provide a visual confirmation of occlusion which does not rely upon color change. It is another object of the invention to provide a visual confirmation which appears or disappears upon occlusion of the closure device.
The prior art includes references which have slits or notches to the surface. Such references include U.S. Pat. Nos. 5,070,584, 5,307,552, 5,363,540 and 5,403,094, and French Patent 2,022,865. However, these references do not use the slits or notches to show visual confirmation of occlusion or unocclusion.
Another object of this invention is to combine visual confirmation of occlusion with a tactile and/or audible indication of occlusion.
For example, the color-change effect is imperceptible in the dark, thus mooting the color-change advantage of the closure devices when they are used under such conditions. In addition, sight-impaired or color-blind people may not be able to perceive the color-change effect. Accordingly, it would be desirable to provide a closure device that affords other indications of occlusion.
The prior art has attempted to furnish a fastener that provides a tactile or audible indication of occlusion. For example, U.S. Pat. Nos. 4,736,496, 5,138,750, 5,140,727, 5,403,094, and 5,405,478, as well as EP 510,797, disclose closure devices that allegedly provide a tactually or audibly perceptive indication of proper interlocking of the closure elements. It is said that, upon occlusion of the disclosed closure devices, a user is able to feel or hear that full closure is accomplished. For example, U.S. Pat. No. 4,736,946 discloses the use of additional ribs on either side of the closure elements. These ribs are said to give an improved “feel” to the closure, thus aiding a user in aligning the closure elements.
The devices shown in these references are able only to provide a dynamic tactile indication of occlusion, that is, the user is able to tactually perceive that the closure device is functioning properly only at the time the user is manually closing the device. Such devices do not provide a static tactile indication of occlusion, that is, they do not “feel” closed after occlusion has been effected. Accordingly, if a plastic bag containing such a closure device is sealed by one person, a second person will not readily be able to tactually determine that the bag is sealed. The ability to make such a determination is desirable.
It is a general object of the present invention to provide visual confirmation of occlusion for a closure device. It is a further general object of the present invention to provide a container that is closeable and sealable by means of such a closure device.